seat runner spacers

[greymrj]

Noticed an earlier thread on seat mounting bolts. When I took the seat out of my S1 I noticed that there were approx 1" spacers between the seat runners and the floor on the passenger side but not on the drivers. Other evidence suggested the driver had been quite tall. I however am only 5'6"! I was intending to use stainless socket head bolts to secure the seat rails to the floor, using an approx 1" spacer and a 3" stainless disc either side of the fibreglass as a load spreader. In the event of an accident I guess it would be the g.r.p. floor rather than the bolts which would fail. Anybody got any comments on this before I get stuck in?
Richard

[Barkychoc]

In an accident the belt takes your weight not the seat.

Chris

[GreenV8S]

Seems to me that what you're suggesting would be stronger than the original installation which just has penny washers to spread the load into the fiberglass. It's all rather dodgy, and I've seen seats ripped out of the floor in an accident leaving the driver vulnerable to being thrown around inside the car. Tower View sell seat brace bars which connect the seat to the chassis. This ensures that the seat stays located in a crash, and it also makes the seat much stiffer which helps keep you located in hard cornering. have you seen how far the standard seats move about when you push them sideways?

[greymrj]

I take your point Barkychoc but I did some rally car prep for a bit and I know what happens if the belts are well anchored and the seat isnt. My S type has never been crashed but when I took the seats out two of the mounting points on the passenger side had obviously been moving for some time and the g.r.p. had lots of fractures and had lost all its strength over at least a 2" diameter. Quite literally, a big bump from a sharp crest in the road and the passengers seat could have come adrift. The drivers seat had collapsed, the driver had effectively been sitting on padding on the floor and the seat mounts havent been taking the strain for some time! Like GreenV8S I have seen how much the seats can deflect on hard cornering, and much of that appears to be flexing of the floor. Part of the problem is that the seats mount to a flat section of g.r.p. which has very little strength. In a steel shell there would be some form of profile to add strength. As I am shorter I will have to raise the seat, that potentially makes the problem worse and I want to ensure my floor/seat arrangement is strong enough to last a long time.
Is there anybody out there of about my height (5'6&quot who can tell me if 1" spacing will be about right?

[Barkychoc]

Agreed - seats should be secure.
In any case you wouldn't want to be hit from behind with dodgy seat fixings - in that case the seat backrest is taking many times your weight with the forces involved during impact.

[ijbd]

Oops,

if we have an idiot driver hitting us from behind, the strength of the seat anchors does matter.

I would expect at least two, say 2 mm thick and 5 cm wide metal plates underneath each runner, sandwiching the floor between the plates. Perhaps the rail can count as the inner plate of this sandwich.
Do not overdo the platethickness (no U profile), the fibreglass remains limiting as mentioned earlier. A too stiff backingplate will concentrate the load on the adjacent fibreglass.
Predrill matching boltholes in the plates.
Install with slowcuring epoxyglue between plate and floor, or bond the plates in place with fibreglass.
With a jack force a wooden beam protected with pvc against the bottomplate when the epoxy dries.

To raise the seat, replace the inner plate with an appropriate thickness wooden beam. Beam preferably with trapezium like crosssection.

mvg Boudewijn